High capacity liquid meter



1963 R. K. FRANKLIN ETAL 3, 71

HIGH CAPACITY LIQUID METER Filed April 2, 1959 4 Sheets-Sheet 1 Robe/fflank/N7 W////am M Bore/7 Robe/'7 6'. 00,0600? INVENTORS Wfi/W ATTORNEY1963 R. K. FRANKLIN ETAL 3,110,171

HIGH CAPACITY LIQUID, METER Filed April 2, 1959 4 Sheets-Sheet 2 SUPPLYI 70 /5 L 70 l4 7 v /7 Robe/*2 A. fiankl/n Wl/ham M .Boren j 4 Robert 6.0/ 0/2002 @INVENTORS 1963 R. K. FRANKLIN ETAL HIGH CAPACITY LIQUID METER4 Sheets-Sheet 3 Filed April 2, 1959 zoo ' INVENTORS ATTORNEY R. K.FRANKLIN ETAL 3,110,171

HIGH CAPACITY LIQUID METER 4 Sheets-Sheet 4 INVENTORS BY M ATTOR/VfyNov. 12, 1963 Filed April 2, 1959 2:: \l: :::P 1 n 7 w M Q I a o UnitedStates Patent 3,119,171 HIGH APACHTY LEQ METER Robert K. 182%} SouthBouierard, William M.

Ber-en, and Robert G. Oliphant, all of Houston, Tex;

said Karen and said Oliphant assignors to Role Iilanu: factoringCompany, iouston, Team, a corporation or Texas Filed Apr. 2, 1959, Ser.No. 803,736 3 Claims. (1. 73-421) Our present invention relates to ahigh capacity liquid meter particularly adapted to determine thequantities of crude oil produced from an oil well, and includes variousspecific embodiments of its principles to resolve special oil fieldproblems involving rapid and accurate metering and simultaneous meteringand separating.

In the art of fluid measurement, it is acknowledged that the highestpractical accuracy is obtained by Volumetric meters, those in which achamber of known volume is alternately filled and dumped. As a result ofextensive research and development, we have invented certain meters andmetering separators which provide accuracy of a high order in automaticfluid handling units. These inventions are disclosed and claimed incopending United States Applications Serial No. 645,163, filed March 11,1957, now Patent No. 3,027,763, and Serial No. 703,782, filed December19, 1957, now Patent No. 3,023,618. Certain features of thoseapplications are incorporated in the devices of the present application,together with means to increase the capacity or rate of fluidmeasurement of a volumetric meter.

In the United States, the production from oil wells is regulated by lawin most areas, and wells are seldom allowed to produce to their fullcapacity. As the output of each Well must be determined separately forcompliance with an established allowable production figure, there hasbeen little demand for a meter capable of handling quantities in excessof 20,000 barrels per day. However, in certain foreign fields wherelegal allowables are unknown, extremely high rates of production from asingle well are not uncommon, and it is also feasible to combine theoutput of several wells in a common separating and metering system. Thusprior volumetric meters with their relatively low capacities have provedunsuitable.

One of the chief capacity limitations of volumetric meters is the lackof continuity of flow. It is necessary to arrest the incoming fluid atregular intervals in order to dump the calibrated metering chamber. Thedump time varies with the installation and depends on the design of themeter with regard to pipe and valve sizes, the means available toaccelerate the discharge, and the viscosity of the fluid. However, it isapparent that even under optimum conditions, there is an inherent delayin a unit which cannot handle a continuous flow therethrough.

The dump time can be reduced by accelerating the discharge by any ofseveral means. For example, a pump may be employed to more rapidlyevacuate the metering chamber, or gas pressure may be applied to themetering chamber to accomplish the same end. It is, of course, necessaryto separate the liquid constituents of the raw well fluid from the gasentrained therein insofar as possible prior to metering. This operationwhich is usually accomplished :by a separate unit in the processingsystem makes its own demands on the available differential head and gaspressure, and thus, the often limited flow acceleration means must becarefully allocated to the point of maximum utility.

An additional limitation on speed of handling results from the highviscosity of certain well liquids. Extreme- 3,110,171 Patented Nov. E2,1963 ice 1y viscous crude oils will exhibit an obvious reluctance toflow rapidly through restricted areas such as pipes and valves. Theimportance of rapid closing valves to accurate volumetric metering isobvious from inspection of the aforementioned patent applications, andthe fact that instantaneous operation becomes increasingly diflicult andexpensive to achieve as the viscosity of the liquid as well as the valvesize increase makes it apparent that the sizes of the conduit between aseparately housed meter and separator and the discharge conduit arelimited. These limitations result in slow meter filling and dischargeand present other problems to be overcome.

The entrained gas in high viscosity crude oils is more likely to resistseparation than that in thinner liquids. Thus it quite often occurs thatthe gas and oil are only partially separated at the time of metering,and the additional treatment necessary to correct this situation isseldom economically justifiable. Rather, it is the practice to measurethe fluid in its partially separated state and allow additionalseparation to occur after the fluid is stored.

These hitherto unresolved problems coupled with the always presentproblems of high accuracy and automatic operation have led to ourpresent invention, the objectives of which may be briefly stated asfollows:

It is an object of our invention to provide an automatic liquid meterwhich is capable of continuous, accurate measurement of large volumes offluid.

It is also an object of 0111 invention to provide a high capacity,volumetric meter which allows continuous anduninterrupted flow ofincoming fluid.

it is a further object of our invention to provide a commonly housedseparator and high capacity meter which is capable of continuouslymetering and separating a large volume of raw well fluid.

It is also an object of our invention to provide a well fluid meteringseparator which is capable of rapid handling of highly viscous fluid.

More specifically, it is an object of our invention to provide a meterand a separator in combination in which the passage of fluid from theseparator to the meter is relatively unobstructed, and a maximum rate ofdischarge is obtained.

Still another object is to provide a high capacity, accurate volumetricliquid metering device, including a liquid seal preventing the loss intothe discharge line of pressured gas provided for expelling the measuredliquid from the meter and for maintaining priming of a pump used forexpediting delivery from the meter.

It is also an object of our invention to provide a high capacityautomatic liquid meter which will yield the external accuracies requiredfor custody transfer, the operation in which volumes of crude oil aretransferred from the custody of one party to another and payment isbased on the number of units so transferred.

Briefly, the above objectives are accomplished by providing a tandem orparallel arrangement in which two similar metering chambers are situatedin a side-by-side relationship and the fluid inlet is adapted foralternate discharge thereinto. By appropriate controls, the flow is sodirected that one chamber is filling while the other is dumping, and bydesign, less time is required to dump than to fill. Therefore, flow intothe meter is continuous, and the chamber into which it is directedalternates depending on the portion of the cycle at which the unit findsitself at a given moment. This novel construction provides a meter, withor without a separator, in which the above outlined advantages obtain,and continuous flow suitable to the needs of large volume producingfields may be handled.

Referring now to the drawings:

FIG. 1 is a vertical transverse section, shown partly 3. schematic, of ahigh capacity meter constructed according to our invention;

FIGS. 2 and 3 are similar views of modified forms of high capacityseparating meters;

FIG. 4 illustrates diagrammatically a control system for the devicm ofFIGS. 13;

FIG. 5 is a view similar to FIGS. 1-3 showing another embodiment of theprinciples of our invention in a high capacity separating meter;

FIG. 6 is a diagram of a suitable control system for the unitillustrated in FiG. 5;

FIG. 7 and 8 are sectional and schematic views of further modificationsof the invention especially adapted as high capacity automatic custodytransfer meters.

The form Olf the invention shown in FIG. 1 includes a casing 12 having acentral partition 13 dividing the casing into separate parallel ortandem measuring reservoirs or chambers 14 and 15. Liquid is supplied tothe top of the casing from an inlet line 16 through a threeway valve,generally indicated as l7, which is controlled by a pneumatic motordevice 18 to alternately supply liquid to the reservoirs 14 and 15. Atthe bottom of the reservoirs are sumps 19 and 20 which are floats 21 and22, respectively, controlling pilot valves 23 and 24 of the controlsystem. Liquid is discharged from the sumps through discharge lines 25and 26, controlled, respectively, by valves 27 and 28, in turn, operatedby pneumatic motor devices 29 arid 3% Discharge lines 25 and 26,ultimately, merge in a single discharge pipe 31. Mounted intermediatelyof reservoirs 14- and 15 and terminating short of the bottom thereof arequieting panels 32 and 33.

This form operates as follows: Assume liquid is being supplied pastthree-way valve 17 into reservoir 15. When this liquid overflowspartition 13 into sump l9, float 21 is lifted so as to reverse pilotvalve 23 which, through pneinnatic connection as shown in FIG. 4,reverses threeway valve 17 so as to cut oil the supply to reservoir 15and direct the inlet liquid into reservoir 14. After a brief delay topermit stabilizing of the liquid level in reservoir 15, discharge valve28 is opened permitting the dumping of the accurately measured quantityof liquid in this reservoir to the discharge pipe 31. When reservoir 15is emptied, float 22 drops and discharge valve 28 is closed. Thecapacity of discharge line 26 and valve 28, preferably, is greater thanthat of inlet valve 17 and the inlet connections to the parallelreservoirs so that reservoir 15 will be fully discharged beforereservoir 14 is filled. Accordingly, when liquid in reservoir 14overflows partition 13, float 22 will be lifted to again reverse theinlet valve and, after -a brief delay, open discharge valve 27 to dumpthe measured quantity of liquid from reservoir 14 into discharge pipe31. These alternating cycles will be repeated as long as liquid issupplied through inlet line 16 and without interrupting this inletsupply.

The form in FIG. 2 is quite similar to that in FIG. 1 except tor theaddition of a mist separator 35 at the top of casing 36. Baffles 32 and33 are, respectively, located substantially in the lines of dischargetrom the liquid inlets so as to facilitate separation of gases from theliquid. Otherwise, the structure and operation of this form is the sameas in the first form and various parts are given the same referencenumerals each with a prime added.

FIG. 3 shows a somewhat diflerently-shaped casing 443 having a centralpartition 13" and centrally-pivoted floats 22" and 21". Pneumatic linesto pilot valves 23" and 2 2" are led through hollow standards 41 and 42which pivota -1y mount the floats. Apertured partitions 43 and 44 assistin the separation of gases from the liquid supplied through the inlets,these gases being directed into a mist separator 45. Other parts aredesignated by the same reference numerals as in FIG. 1, but each with adouble prime.

4 FIG. 4 shows, diagrammatically, the pneumatic control system for theforms in FIGS. 1, 2 and 3. In FIG. 4, the alternate flow lines throughthe various valves are shown, respectively, in solid and dotted lines,as will be A explained. The essential elements of this control are fourmaster valves 59, 51, 52 and 53, each pneumatically operated in oppositedirections by pressure chambers, designated a and b, respectively, onopposite ends of the valves. Valve 5%} is a four-way valve and valves51, 5-2 and '53 are three-way valves, the alternate paths of fluidthrough the valves being indicated by solid and dotted lines. Anunderstanding of the control may be derived from a consideration of itsfunctioning as follows: With both floats 21 and 22 down, assume mastercontrol valve 50 for inlet switching valve 17 is in its solid flow lineposition to direct pressure from line 55 into the bottom of motor 13 andadjust valve 17 to direct oil into measuring reservoir 15 at the rightside of partition 13. As float 22 lifts and pilot 24 moves to the solidflow line position, gaseous pressure from supply line 54, 55 is admittedto chambers Z; of master valves 51 and 52 so as to shift these valvesleftwardly. Chambers a of the valves are exhausted through the solidflow lines of pilot valve 23, float 21 being down. In the leftward,solid flow line position of master valve 51 with float 21 down and pilotvalve 23 in its solid flow line position, pressure from line 54 is cutoff from control motor 39 of discharge valve 28 and this valve is closedby its spring. In the leftward position of master valve 52 (solid flowline position) with float 22 up, pressure from line 55 and pilot valve24 is cut off from control motor 2? of discharge valve 27, and thisvalve remains closed.

As measuring reservoir 15, fills and overflows into reservoir 14, float21 in the latter is lifted to shift pilot 23 to the dotted flow lineposition so as to direct pneumatic pressure from line 54 to chambers aof master valves 51 and 52, but these master valves are not shiftedsince opposite pressure chambers 1) thereof remain pressured. Controlchamber a of master valve 53 and the counter are exhausted. Pressurefrom line 54- is also directed through master valve 51 (still in itssolid flow line position) to motor 30, so as to open discharge valve 28after a brief interval, as determined by the seating of a one-way checkvalve restriction 57, and to pressure chamber b of master valve 5%shifting valve 5%; to the dotted flow line position and, thereby,reversing feed valve.

17 to cut oil the supply of liquid to reservoir 15 and, at the sametime, direct the incoming liquid into reservoir 14.

Reservoir 14 now starts to fill while reservoir 15 drains its measuredquantity of liquid. When float 22 in the latter reservoir drops, itscontrolled pilot valve 24 rotates to the dotted flow line position so asto exhaust chambers b of master valves 51 and '52 which permits both ofthese master valves to shift rightwardly to their dotted flow linepositions. At the same time, control chamber [7 of master valve 53 ispressured, shifting this valve left-- ward-ly to its dotted flow lineposition to apply a counting impulse to counter 56 and the cycle nowcompleted is repeated.

in the form in FIG. 5, casing 60* is provided with a central partition61 dividing the casing into separate reservoirs 62 and 63. Within thereservoirs, there are provided generally L-shaped separating baifles64-, 65 which depend nearly to the bottom of the casing and form quietchambers therebeneath. in each quiet chamber 62a, 63a, there is receiveda float 66, 67 which is slidable on a ver-- tical rod 63, 6?. These rodshave stops 79, '71 and '72, 73 and, at their upper extremities, areconnected to levers 74,. 75 which operate pilot valves '76 and 77.

Tubes 73 and 79 direct gases trapped beneath separating partitions 64and 65 into the upper part of the main casing where, together with othergases separated from the incoming liquid, they are passed through mistseparator device 8@ and gas outlet 81. Partitions 82 and 83 abreastinlet ports 84, 85 facilitate separation of gases from the liquidsemerging from the inlets. At the bottom of the casing, discharge lines36 and 87 merge in a common discharge pipe 88. These discharge lines arecontrolled, respectively, by valves 39 and 4) actuated by pneumaticmotor devices 91 and 22. The discharge ports are provided withprotecting screens or baffles 93 and 94. Liquid is admitted to thecasing rough a three-way valve 95 actuated by a pneumatic motor $6.

In operation of the form in FIG. 5, three-way valve 95 alternatelydirects inlet liquid into one or the other of chambers 62 and 63. Thisliquid drops down through one of the ample passages 62b, 63b and thencepasses upwardly into corresponding quiet chamber 62:: or 63a. When thefloat is lifted sufficiently, it engages upper stop 70 or 72 to actuatepilot valve 76 or 77. This causes opening of a discharge valve 89 or 9%and shifting of inlet valve 95 to direct the inlet fluid into theopposite reservoir. When the measured volume of liquid in the reservoiris discharged and the float drops, engaging one of the lower stops 71 or73, the open discharge valve is closed preparatory to another switchingof three-way inlet valve 25 to again direct inlet fluid into the firstreservoir to repeat the cycle.

FIG. 6 shows a pneumatic control system for the form of meter in FIG. 5.The control includes a single master or slave valve 160 having oppositepneumatic control chambers a and b and in which the alternate flow pathsare indicated, respectively, by solid and dotted lines, as will beexplained. The parts are shown just subsequent to shifting, withactuating diaphragm motors a and b in their leftward positions to openthe solid flow lines and direct pneumatic pressure from the supply lines2% to the bottom of motor 96. This places three-way valve 95 in acondition to cause inlet oil to be cut oil from reservoir 63 anddirected into reservoir 62 at the left side of partition 61. Thisshifting of valve 95 is effected as lever 75 is lifted by float 67. Atthe same time, pressure is supplied from source 2% and line 291 topneumatic motor ?2 for opening discharge valve 99 so as to direct themeasured quantity of liquid in reservoir 63 into the discharge line.FIG. 6 shows opposite float 66 dropped and its pilot valve 76 in aposition to exhaust lefthand pneumatic chamber b of master valve 1% :topermit the justmentioned leftward movement of the master valve.

When float 67 drops, indicating emptying of metering chamber 63, pilot77 will move to cut ofi pressure from slave valve motor a, and thisvalve will remain in its leftward position. However discharge valvemotor $2 is exhausted through line 291 and valve '77, closing va.ve 91As soon as opposite float 65 is fully lifted and its pilot valve 76thereby reversed, the consequent supply of control pressure through line202 to chamber 2) of the master valve will shift the latter rightwardlyto its dotted flow line position. This will direct pneumatic pressurefrom line 2% to the top of motor 96 to shift inlet control valve 95,returning the inlet delivery to reservoir es. This motion of the mastervalve also will apply pneumatic pressure to motor 91 to open dischargevalve 89. The discharge lines are of at least as great capacity as orgreater capacity than the inlet connections to insure complete dischargeof each metering chamber before the opposite metering chamber is filled.This insures continuous supply through the inlet and, accordingly,maximum capacity of the meter.

FIG. 7 shows a tandem meter with liquid seal which is well adapted toserve as a high accuracy, high capacity custody transfer meter. Thismeter consists of a main casing 161 having a central partition 1G2dividing the casing into metering reservoirs or chambers 193 and 164. inthe tops of these metering chambers are overflow chambers 1G5 and 1%having therein, respectively, floats 107 and 108 actuating pilot valves1%? and 11%. Below the outwardly inclined bottom walls of meteringchambers 103 and 10 which facilitate complete draining thereof, is aliquid seal chamber 111 in which is received a float 112 actuating apilot valve 113. Oil inlet line 1-14 is connected to a three-way valve115 which, as indicated, selectively directs the inlet supply to one ofmetering reservoirs 103' or 1%. Chambers 163 and 104, respectively, areconnected to the seal chamber by drain passages 116 and 117 controlledby dump valves 118 and 119, provided with actuating pneumatic motors 12%and 121. The sea chamber is provided with a vent line 122 containing avalve 123 actuated by a pneumatic motor 124. The vent line terminates ina vent chamber 125 containing a float 126 which actuates a pilot valve127, and a balancing connection 127' to the top of the main casing.Discharge line 128 at the bottom of the seal chamber is controlled by adischarge valve 129 actuated by a pneumatic motor 131?. Inclined topwall 131 of the seal chamber facilitates venting of all gases from thischamber. Transfer passages 132 and 133 connect the overflow chambers tothe metering reservoir. These passages are controlled by valves 134 and135 actuated by pneumatic motors 136 and 137.

The operating cycle of this meter is as follows: Initially, all fourfloats 1W, 1%, 112 and 125 are down. Assume that inlet valve 115 is inposition to direct liquid into measuring reservoir 103. The dumping line117 between opposite reservoir 1414 and seal chamber 111 is closed, aswill be the dumping connection 116 and discharge valve 129. Ultimately,the liquid in chamber 168 will overflow into chamber 1175 a1 1d liftfloat 167. This float action, through its pilot valve and operativeconnections will cause shifting of inlet valve 115 to cut off the supplyof oil to reservoir 1% and direct the supply to reservoir 10%. The sameaction of float 107 will open dump valve 118, so that the measuredquantity of liquid in reservoir 1% will be discharged into liquid sealchamber 111 through passage 116. This discharged liquid will fill sealchamber 111, lifting float 112, and also will enter vent 122, throughopen vent valve 123, and vent chamber 125'. When vent chamber float 126is lifted, indicating exclusion of all gas from chamber 111, its pilotvalve 127 will be actuated so as to cause, through suitable operativeconnections, opening of discharge valve 129. This continues thedischarge part of the cycle started upon reversal of valve 118.Coincident with opening of the discharge valve, vent valve 123,optionally, may be closed to exclude casing gas from the seal chamber.If desired, this delivery of liquid to the discharge line may beexpedited by gas pressure in the top of casing 1%, or by a pump in thedischarge line. In the former case, vent line .127 insures balancing ofpressures in casing 1113 and chamber 125 during initial dumping from themeasuring chamber. in either case, however, float 112 will drop beforethe seal chamber is completely empty, closing discharge valve 129. Thiswill prevent the discharge of gas from the meter into the discharge linewhile maintaining a prime in the discharge pump, where provided.

When discharge valve 129 is closed, dump valve 118 will close, ventvalve 123 will be re-opened so as to drop the oil remaining in the ventline and chamber 125 into seal chamber 111, and transfer valve 134 willbe actuated for a short period, by its motor 136 and operativeconnections to seal chamber float valve 113 to drain liquid fromoverflow chamber 105 into metering reservoir 193 where it joins theinlet supply being measured. During the discharge operations, filling ofopposite meter reservoir 1114 will continue until overflow into chamber1% actuates float 168 to repeat the overflow and discharge cycle. As inthe previous forms, the dumping and discharge lines and valves are ofgreater capacity than the inlet lines to insure emptying of themeasuring and seal chambers before actuation of the overflow float inthe particular metering reservoir being filled reverses the inlet supplyand initiates the dumping of the measured quantity of liquid. Upondraining of reservoir 1G4 and and metering action.

immediately subsequent dropping of seal float 112, dump valve 119 isclosed, vent valve 123 is opened, and drain valve 155 is momentarilyopened to prepare reservoir M4- for the next metering cycle initiated bylifting of opposite overflow float Hi7.

PEG. 8 shows a tandem meter incorporating, in general the principles ofFIGS. l3, and also including a liquid seal chamber. As before, the maincasing 14% is divided by a partition 141 into metering reservoirs 142and 143 containing floats 144 and 145 in their lower portions. Thefloats, respectively, control piiot valves 46 and 147. Below theinclined bottom walls of reservoirs 142 and 143, is a liquid sealchamber 148 containing a float 149 which actuates a pilot valve 159. Avent line 151 leads from the seal chamber through a normally-open ventvalve 152, with an actuating pneumatic motor 153, to a vent chamber 154containing a float 155 which actuates a pilot valve 156. A vent linecontinuation connects the top of the vent chamber to the top of the maincasing for equalizing the gas pressures therein. Oil inlet line 158connects through three-way inlet valve 159 with either of the lines 161or 168 leading to the respective metering reservoirs 142 and 143, inaccordance with the position of valve 159. Valve 159 has an actuatingpneumatic motor 162. Chambers 143 and 142 may be dumped through fluidconnections 164 and 165 with the seal chamber, having control valves 166and 167 with actuating motors 16S and 169. Discharge from the sealchamber is through line 17% and normally closed dis charge valve 171having actuating motor 172.

The operating cycle of this form is as follows: Assume inlet valve 159is in position to direct inlet oil into reservoir 142 which hasoverflowed into reservoir 143 so as to lift float 144. This causes,through suitable operating connections, shifting of inlet valve 159 tocut off the inlet supply to reservoir I142 through line 1st and directthis supply into reservoir 1 2-3 through line 160. At the same time,dump valve 167 will be opened and the measured quantity of liquid inreservoir 142 will be dumped through line ltSS into liquid seal chamber148. Ultimately, the seal chamber will be filled, lifting float 149, andliquid will pass through vent line 7.51 and open valve 152 into chamber15-4 where float 155 will be lifted. This will act through pilot valve156 to open discharge valve 171 and, optionally, close vent valve 152.When the liquid in seal chamber 143 and the remaining liquid in meteringreservoir 142 are drained out and discharged, permitting seal chamberfloat 149 to drop, discharge valve 171 and dump valve 15,7 are closedand vent valve 152,

optionally, re-opened to permit the liquid remaining in the vent chamberto drop into the seal chamber. Reservoir 142 will now be empty ready toreceive the overflow from reservoir 143, as in the beginning of thecycle described.

The metering arrangement of FIGS. 7 and 8 as Well as of FIGS. 1, 2, 3,and 5, may be provided with any suitable control connection between thevarious floats and valves, whether pneumatic, electrical, or hydraulic,for accomplishing the operating cycles, as described. Each of the formsof the meter incorporates the tandem principle for insuring continuousflow through the inlet line while the measuring reservoirs alternatelyfill and empty. Since, by design, the discharging valves and passagesare of at least as great capacity as or greater capacity than the inlet,there will be no interruption of the inlet flow It would, of course, bepossible to provide three or more metering reservoirs in tandem if theinlet rate were sufliciently large to justify this in view of thenecessary limitations of valve sizes to insure rapid action of thevalves. The forms in FIGS. 13 and 7 and 8, utilizing the overflowprinciple for obtaining an accurately measured volume of liquid, will besomewhat more accurate than the form in Pi 5 which is subject toinaccuracies of float action. Each of the meters, however, is welladapted for measuring high capacity flows and, due to the relativelylarge inlet ducts within the meter itself, to handle viscous oils. Theaddition of mist separator, as in FIGS. 2, 3 and 5, which feature couldbe added to any of the forms, equips the meter for handling oils withsubstantial gas content. The liquid seal feature permits the use ofgaseous pressure within the meter for expediting discharge therefrom,without the danger of the pressured gas escaping into the dischargeline, and also insure the exclusion from the discharge of volatileconstituents carried from the metering chambers. The seal alsofacilitates the use of a discharge pump by avoiding the danger of gasbeing drawn into the pump and discharge line. The structures shown maybe modified in various respects as will occur to those skilled in theartand the exclusive use of all modifications as come within the scopeof the appended claims is contemplated.

We claim: 1. A liquid meter comprising a closed casing with partitioningmeans defining first and second liquid measuring reservoirs therein, aliquid seal chamber directly below said reservoirs in the lower part ofsaid casing, devices associated with said reservoirs for registering thevolume of liquid therein, inlet ducting connected to said reservoirs,outlet ducting connected to said seal chamber, means for maintaining insaid seal chamber sufficient liquid to seal said outlet ducting and saidseal chamher at all times, transfer passages, respectively, between saidreservoirs and said seal chamber, valves controlling said transferpassages and said inlet and outlet ducting, and operative connectionsbetween said volume registering devices and said valves for initiallyopening said inlet ducting into said first reservoir while opening thetransfer passage between said second reservoir and said seal chamber,then opening said outlet ducting, then, when said second reservoir isdrained and said first reservoir is filled, cutting oif said outletducting and said inlet ducting leading to said first reservoir and saidtransfer passage between said second reservoir and said seal chamber,

then opening said inlet ducting leading to said second reservoir,

then opening the transfer passage between said first reservoir and saidseal'chamber,

and finally re-opening said outlet ducting whereby measured quantitiesof liquid are alternately discharged from said reservoirs and saidcasing while liquid is continuously supplied to said casing through saidinlet ducting.

2. A liquid meter comprising a closed casing with partitioning meansdefining a plurality of side-by-side chambers therein,

inlet and outlet ducting connected to certain of said chambers,

floats in certain of said chambers each for reacting to overflow fromanother chamber to signal filling of said other chamber,

a liquid seal chamber in the lower part of said casing and directlybeneath said last-mentioned chambers,

transfer ducts, respectively, between said last-menti0ned chambers andsaid seal chamber,

each of said transfer ducts having valves,

a discharge duct with a valve leading from said seal chamber,

means in said seal chamber for maintaining suflicient liquid therein toseal said discharge duct from casing gases at all times,

and operative connections between said floats and said inlet, transfer,and discharge valves for first opening said inlet ducting to a first ofsaid first mentioned chambers and substantially concurrently closing thetransfer duct valve from said first chamber While cutting off said inletducting to a second of said first mentioned chambers,

then opening said discharge valve to drain the measured quantity ofliquid from said seal chamber,

then closing said discharge valve,

then reversing said inlet and transfer duct valves,

and, finally, again opening said discharge valve long enough to drain asecond measured quantity of liquid from the casing to complete the cycleduring continuous flow through said inlet duct into said casing.

3. A liquid meter as described in claim 2, wherein,

said side-by-side chambers define first and second reservoirs separatedby a weir and said floats are each located near the lower portion of therespective chamber for signalling filling of the other chamber to enableeach chamber to function References Cited in the file of this patentUNITED STATES PATENTS 1,521,391 Roach et a1 Dec. 30, 1924 2,831,350Banks et al Apr. 22, 1958 2,876,641 Brown Mar. 10, 1959 2,954,693 NelsonOct. 4, 1960 OTHER REFERENCES Shells Proposal in an article entitledAutomatic Custody Transfer in Texas in the Oil and Gas Journal, July 30,1956, vol. 54, No. 48, pp. 122, 123.

1. A LIQUID METER COMPRISING A CLOSED CASING WITH PARTITIONING MEANSDEFINING FIRST AND SECOND LIQUID MEASURING RESERVOIRS THEREIN, A LIQUIDSEAL CHAMBER DIRECTLY BELOW SAID RESERVOIRS IN THE LOWER PART OF SAIDCASING, DEVICES ASSOCIATED WITH SAID RESERVOIRS FOR REGISTERING THEVOLUME OF LIQUID THEREIN, INLET DUCTING CONNECTED TO SAID RESERVOIRS,OUTLET DUCTING CONNECTED TO SAID SEAL CHAMBER, MEANS FOR MAINTAINING INSAID SEAL CHAMBER SUFFICIENT LIQUID TO SEAL SAID OUTLET DUCTING AND SAIDSEAL CHAMBER AT ALL TIMES, TRANSFER PASSAGES, RESPECTIVELY, BETWEEN SAIDRESERVOIRS AND SAID SEAL CHAMBER, VALVES CONTROLLING SAID TRANSFERPASSAGES AND SAID INLET AND OUTLET DUCTING, AND OPERATIVE CONNECTIONSBETWEEN SAID VOLUME REGISTERING DEVICES AND SAID VALVES FOR INITIALLYOPENING SAID INLET DUCTING INTO SAID FIRST RESERVOIR WHILE OPENING THETRANSFER PASSAGE BETWEEN SAID SECOND RESERVOIR AND SAID SEAL CHAMBER,THEN OPENING SAID OUTLET DUCTING, THEN, WHEN SAID SECOND RESERVOIR ISDRAINED AND SAID FIRST RESERVOIR IS FILLED, CUTTING OFF SAID OUTLETDUCTING AND SAID INLET DUCTING LEADING TO SAID FIRST RESERVOIR AND SAIDTRANSFER PASSAGE BETWEEN SAID SECOND RESERVOIR AND SAID SEAL CHAMBER,THEN OPENING SAID INLET DUCTING LEADING TO SAID SECOND RESERVOIR, THENOPENING THE TRANSFER PASSAGE BETWEEN SAID FIRST RESERVOIR AND SAID SEALCHAMBER, AND FINALLY RE-OPENING SAID OUTLET DUCTING WHEREBY MEASUREDQUANTITIES OF LIQUID ARE ALTERNATELY DISCHARGED FROM SAID RESERVOIRS ANDSAID CASING WHILE LIQUID IS CONTINUOUSLY SUPPLIED TO SAID CASING THROUGHSAID INLET DUCTING.